Since its April 13 release, "I Just Want You to Know: Letters to My Kids on Love, Faith, and Family" has sold just 10,084 copies, according to national book sales tracker Bookscan. The non-fiction title debuted at #11 on the New York Times' non fiction bestseller list, and at #103 on USA Today's bestsellers chart. By Thursday afternoon, its Amazon.com rank was #862.

This is in spite of Gosselin's relentless promotion of the tome on TV and radio -- plus her ubiquitous presence on "Dancing with the Stars" prior to her ouster last week.

Jim Milliot, business and news director of book-industry magazine Publishers Weekly, tells UsMagazine.com that the numbers "nowhere near a blockbuster" and "not that impressive."

By contrast, the 35-year-old mom's first two books, "Multiple Blessings and Eight Little Faces," both climbed to number five on the New York Times' list; Multiple Blessings sold 523,000 copies in 2009.

Could "I Just Want You to Know" end up selling 500,000 copies in the long run? Not likely, Milliot tells Us, explaining that the lion's share of book sales typically occur "in the first month or two of publication." He adds that Gosselin will have "a very tough time getting to 50,000, let alone 100,000 ... I think it will be a disappointment in the end."

The book "continues [Kate's] story of faith and family," an Amazon description reads. "Using excerpts and written prayers from her journal, Kate offers an intimate look at the heart of a mother during the three years her family transitioned from obscurity into television fame."